Elimination of isolated pores during liquid phase sintering of Fe_Cu alloys have been investigated. Large spherical pores have been created by sintering the mixtures of Fe powders of 6-8μm, Cu powders of -22μm and large spherical Cu particles of 105-127μm in diameter. During liquid phase sintering, large Cu particles have flowed completely into the capillaries between Fe particles leaving spherical pores of nearly the same size. After prolonged sintering, these large spherical pores have been filled by liquid as shown in W_Ni alloy by Kwon and Yoon.
The effects of liquid content and sintering temperature on pore elimination have been also investigated in 75Fe_25Cu, 80Fe_20Cu and 85Fe_15Cu alloys by wt.%. The rate of pore filling increased with liquid content, and as sintering temperature changed from 1125℃ to 1250℃, the rate increased in 75Fe_25Cu alloy, but decreased surprisingly in 80Fe_20Cu and 85Fe_15Cu alloy. This might be due to the slower rate of shape accomodation, because the particle size is greater and the skeleton between the particles is stronger in the specimen sintered at 1250℃ than in the specimen sintered at 1125℃. Also, the effect of oxidized powder has been investigated by using artificially oxidized powder mixture of 80Fe_20Cu composition. When the oxidized powder has been used, the rate of pore elimination has decreased, and very large irregular pores of a few hundred micrometers and fine pores between the solid particles have been observed.
